DOCS: New Timing and Latency section (DOCF-1179)

Packages/com.unity.inputsystem/Documentation~/TableOfContents.md

@@ -25,6 +25,13 @@
     * [Events](Events.md)
     * [Layouts](Layouts.md)
     * [User Management](UserManagement.md)
+    * [Timing And Latency](TimingAndLatency.md)
+        * [Input Events Queue](TimingInputEventsQueue.md)
+        * [Select an Input Processing Mode](TimingSelectMode.md)
+        * [Optimize For Dynamic Update](TimingOptimizeForUpdate.md)
+        * [Optimize For Fixed Update](TimingOptimizeForFixedUpdate.md)
+        * [Avoid Missed or Duplicate Events](TimingAvoidMissedOrDuplicateEvents.md)
+        * [Mixed Timing Scenarios](TimingMixedScenarios.md)
 * [Supported Input Devices](SupportedDevices.md)
   * [Pointers](Pointers.md)
       * [Touch support](Touch.md)

Packages/com.unity.inputsystem/Documentation~/TimingAndLatency.md

@@ -0,0 +1,14 @@
+---
+uid: timing-latency
+---
+# Timing and Latency
+
+Input Timing refers to the topic of exactly when the Input System receives and processes input from devices.
+
+Latency is the amount of time between the user providing some input, and the user receiving a response to that input. For example, the time between a button press and your game’s character moving on-screen. In fast-paced input scenarios such as action games, even tiny delays between the user's input and your game responding can be noticeable and affect the feel of your gameplay.
+
+In addition to the effects of latency, timing can affect one-off discrete events such as when a button press starts or finishes. Checking for these at the wrong time can result in [missed or duplicate events](TimingAvoidMissedOrDuplicateEvents.md).
+
+To minimize input latency, and to avoid missed or duplicate events, it helps to understand how the Input System processes events in relation to Unity's frame updates, physics updates, and fixed updates. This will help you make decisions about how to read and respond to input in your game or app.
+
+Usually, to achieve minimum latency, set the Input System **Update Mode** to **Process Events in Dynamic Update**, even if you're using code in FixedUpdate to apply physics forces based on input. In physics-based or FixedUpdate scenarios in particular however, there are details to be aware of to avoid issues described above, or which might cause you to choose a different update mode, explained in the following sections.

Packages/com.unity.inputsystem/Documentation~/TimingAvoidMissedOrDuplicateEvents.md

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+# Avoid missed or duplicate discrete events
+
+Discrete events are simple on/off events that occur when a user presses or releases a control such as a gamepad button, key, mouse, or touch press. This is in contrast to continuously changing values like those from gamepad stick movement. You can poll for these types of discrete event by using `WasPressedThisFrame` or `WasReleasedThisFrame`. However, you can get incorrect results such as missing an event or appearing to receive multiple, if you check for them at the wrong time.
+
+If your Update Mode is set to **Process in FixedUpdate**, you must ensure that you only use `WasPressedThisFrame` or `WasReleasedThisFrame` in **FixedUpdate** calls. Using them in Update might either miss events, or returns true across multiple consecutive frames depending on whether the frame rate is running slower or faster than the fixed time step.
+
+Conversely, if your Update Mode is set to **process in Dynamic Update**, you must ensure that you only use `WasPressedThisFrame` or `WasReleasedThisFrame` in `Update` calls. Using them in `FixedUpdate` might either miss events, or return true across multiple consecutive frames depending on whether the fixed time step is running slower or faster than your game’s frame rate.
+
+If you find that you're missing events that should have been detected, or are receiving multiple events for what should have been a single press or release of a control, the reason is probably that you either have your Input Update Mode set to the wrong setting, or that you're reading the state of these events in the wrong `Update` or `FixedUpdate` call.